Help me understand why is this spot so cold/drafty?!?

[Billbill84]

Hi guys. Well as most you probably already know from some of my old posts, for whatever reason, my upstairs in winter is cold as heck. There's a few things going on here that contributes to that, but that's not really what I'm zeroing in on right now because today while it was super windy out, I discovered a something else that's wrong, and likely the main factor of the coldness.

While putting plastic over a window on thee coldest room, i stepped back into the room's corner and it felt like the carpet was wet!! I immediately look down and can see dark air draft staining along the edge where carpet goes under baseboard. I grabbed pliers and tore the carpet back and holy sweet Jesus, the gap underneath baseboard and atop subfloor was literally blowing in with cold air!!!! I mean, that little gap that the edge of carpet was tucked into (baseboard/subfloor), has small dust debris and I could see the debris being blown around.

Why on earth would this spot along most of the length of whole wall be so drafty??? I never thought in a million years that I'd ever notice a draft from such a strange spot on the second floor. Here's a couple pics to show the area. What's the way to access this and how shall I tackle this one? There's really no good access point other than from inside so for starters I might pull baseboard and cut out a 2"x6" piece of drywall to see if maybe slamming some foam in there is the only option. Idk

 

[Jeff Handy]

Looks like your soffits are letting a draft blow in right there.

I would wait for nicer weather, then remove the panels from the soffits and address the problem from the outside.
It should be easy to get up in there to see what’s going on.

Easier and better than cutting out drywall.

Maybe there is a gap in the sheathing that just needs a small strip of plywood applied over it?
Or you can add some solid foam board, spray foam, or combination of all of these fixes.

 

[Billbill84]

Looks like your soffits are letting a draft blow in right there.

I would wait for nicer weather, then remove the panels from the soffits and address the problem from the outside.
It should be easy to get up in there to see what’s going on.

Easier and better than cutting out drywall.

Maybe there is a gap in the sheathing that just needs a small strip of plywood applied over it?
Or you can add some solid foam board, spray foam, or combination of all of these fixes.

That's a good idea! I'm wondering if it's them same soffits that are responsible for that upstairs being so cold in winter and so hot in summer?? That may be the heart of the problem! I'm wondering if there's something I can stick up there from the outside temporarily. Maybe rip some 1/4" foam to fit and figure out how to stick them up.
Them soffits don't really seem to have much of a purpose anyway because if u look at the pics again, that entire sloped section even on the other side of that room doesn't go anywhere so what's it venting? The rim joist between first and second floors? Seems pointless.

 

[Jeff Handy]

They probably have some kind of continuous air space connection to other attic or roof space venting, even just a channel or shoot somewhere.

The small roof section above them has shingles, which need cooling, so I expect that air is flowing in and up and out from there.

You can pull the panels off from the trim channels pretty easy, they might be stapled, or have some tiny nails or screws, sometimes some sections are just a friction fit, hanging on their neighbors.

 

[Billbill84]

They probably have some kind of continuous air space connection to other attic or roof space venting, even just a channel or shoot somewhere.

The small roof section above them has shingles, which need cooling, so I expect that air is flowing in and up and out from there.

You can pull the panels off from the trim channels pretty easy, they might be stapled, or have some tiny nails or screws, sometimes some sections are just a friction fit, hanging on their neighbors.

Yeah when I was caulking up the window below them I remember lightly punching on them and they are up there super tight. I don't recall seeing any staples or nails.
Last time I was in the attic space that's closest to this area I couldn't even access it because of how that upstairs cold room is framed on the inside of the attic. I'm going to get up there again today to recheck maybe I missed something. I'll grab some more pics from that attic

 

[Jeff Handy]

When you get some soffit panels off, you can shine some bright lights in there at night, and see if any of that light is visible from the attic above.

But there could still be a good vent connection, even if you can’t see light.

 

[Billbill84]

When you get some soffit panels off, you can shine some bright lights in there at night, and see if any of that light is visible from the attic above.

But there could still be a good vent connection, even if you can’t see light.

Ok sounds good. I was totally unaware that them vents had to be there because of the fact the roof, although small, is shingled. Is this some kind of roofing code?

 

[nealtw]

Roll the carpet back and caulk the bottom wall plate to the floor.
Outside is attic space, there or may not be sheeting there. But caulking that bottom plate out there would help too.